Highway crossing gate control system for railroads



Oct. 23, 1962 c. T. JACKSON HIGHWAY CROSSING GATE CONTROL SYSTEM FORRAILROADS Filed July 1, 1958 2 Sheets-Sheet 1 m9 mm LR W Y R. E ms N mwo T m .H 1 C m 3 \mm L E fl .m

m m N Oct. 23, 1962 c. T. JACKSON 3,069,312

HIGHWAY CROSSING GATE CONTROL SYSTEM FOR RAILROADS HIS ATTORNEY UnitedStates Patent 3,060,312 HIGHWAY CROSSING GATE CONTROL SYSTEM FORRAILROADS Carlton T. Jackson, Conesus, N.Y., assignor to General RailwaySignal Company, Rochester, N .Y. Filed July 1, 1958, Ser. No. 745,935 6Claims. (Cl. 246-130) This invention relates to railroad highwaycrossing gates and more particularly relates to an electricallycontrolled hydraulically operated gate mechanism.

In automatically operated railroad highway crossing gates of thisgeneral character, the gate arm is normally held in an upright clearposition to permit highway traific to cross the railroad tracks. Uponthe approach of a train, the gate arm is lowered to a horizontalposition to extend across the highway to block traffic. In someinstances, a crossing gate is located on each side of the highway onopposite sides of the railroad track so that the traflic lane in onedirection is blocked by one gate whereas the traflic lane in the otherdirection is blocked by another gate. In other instances, the gate armmay be long enough to block the entire highway.

In either case, with modern highways having increased width, longer gatearms are required which means that more mass must be moved in aneflicient manner to prevent damage to the gate arms and mechanism. Also,the snow and sleet problems add greater weight to the longer gate armsand the force of the wind, whether in hue or against the gate armmovement, severely affects the speed and steadiness of the gate armoperation and places severe strain on the operating mechanism.

The present invention proposes a railroad highway crossing gate which isefiiciently operated by hydraulic power and electrical control in amanner whereby the gate arm movement is kept under complete control atall times regardless of operating conditions. Also, there is providedmeans to insure a slower smooth starting motion of the gate arm,increased acceleration through the in termediate movement, and a slowersmooth stopping motion when the gate arm has reached its intendedposition. This mode of operation thus tends to prevent gate arm andmechanism damage due to abrupt starts and stops of long and possiblyoverweighted gate arms.

Generally speaking, the gate arm operating mechanism is powered by ahydraulic cylinder containing a piston and piston rod arranged to havehydraulic fluid under pressure applied to either one side or the otherof the piston in accordance with the direction of movement desired. Suchfluid is supplied from a pressure accumulator which is automaticallycharged when the pressure falls below a given setting. A sump reservoiris also provided to maintain the fluid supply and receive the dischargefluid.

The piston rod is pivotally attached to a crank arm which is secured tothe gate arm operating shaft and so arranged that movement of the pistonwill rotate the crank arm and cause the gate arm to rotate withinits'limitations of approximately 90 between a horizontal position and avertical position.

Also operated by the crank arm is a throttle valve which is effectivefor each direction of movement of the piston. This throttle valve isconnected to the crank arm by suitable linkage and is so arranged thatwith full hydraulic pressure on one side of the piston, the throttlevalve controls the rate of discharge of fluid on the other side of thepiston and thus regulates the speed of movement' of the piston. Thethrottle valve is constructed and so regulated as to permit a slow speedstarting'movement, a rapid speed intermediate movement and a greatlyreduced speed movement as the stop position in either direction isapproached.

3,060,312 Patented Oct. 23, 1962 Suitable electromagnetic, hydraulic andmanually restricted valves are employed to regulate the flow ofpressurized fluid to the hydraulic cylinder and control the flow of thedischarge fluid back to the sump reservoir, as will be explained indetail hereinafter. Various cams which operate with the gate arm shaftcontrol the movement of electrical contacts which are used inconjunction with the track circuit to control the operation of theelectro-magnetic valves.

The vertical clear position of the gate arm is its normal position andan electro-magnetic hold-clear valve and a pilot operated hydraulicfour-way valve are provided to maintain fluid pressure on the so calledup-side of the piston so that the gate arm will hold its verticalposition under normal conditions. However, the gate arm iscounterweighted so that due to gravity it would normally assume ahorizontal danger position in case of a power failure which would renderthe hold-clear valve ineffective. Under normal operating conditions, thepresence of a train in the crossing gate track section will also renderthe hold-clear valve ineffective and permit the gate arm to start itsdescent to a horizontal danger indicating position due to its gravitybias.

Although it is contemplated that the normal operation of the gate arm toa horizontal position would be a gravity biased movement, anotherfeature of the present invention is the provision of a means whereby thegate arm would be power driven to a horizontal position in the eventthat the gravity biased movement exceeded a certain indicated timeinterval. Such a power driving means can also be adjusted to provide fora full time positive drive to the horizontal position if desired.

Another feature of the present invention is the provision of a pressureaccumulator and an automatic means for keeping it constantly charged sothat fluid under pressure is normally available to facilitate immediategate operation, except under extreme circumstances where too frequentoperation would be limited by the accumulator capacity.

Still another feature of the present invention is the provision of amanifold unit which, when inserted between the hydraulic four-way valveand the operating hydraulic cylinder and bolted thereto, vw'll comprisean assembled unit which connects the majority of fluid passages and thuseliminate many external piping connections.

Other objects, purposes and characteristic features 'of the presentinvention will be in part obvious from the accompanying drawings and inpart pointed out as the description of the invention progresses.

In describing the invention in detail, reference will be made to theaccompanying drawings wherein the invention has been showndiagrammatically rather than in detail, more for the purpose ofillustration and understanding, and in which the different parts arereferred to by distinctive reference characters. Due to limitations insize, the single illustration has been shown on two sheets of drawingand designated FIGS. 1A and 1B. When placed one above the other withFIG. 1A ontop, the similarly marked wires and the gate arm operatingshaft will be in line and may be connected together with pencil lines toform a complete showing of the invention.

Referring now to the drawing illustrations, there 'has been showndiagrammatically in FIG. 1A a single rail-. road track RT having ahighway H crossing thereover. The railroad track RT is provided with theusual insulated joints 1 at or near the center of the highway crossingso as to divide the railroad track into track sections A and B. Thesetrack sections A and B are provided with the usual highway crossingcontrol circuits whereby the entrance of a train into a particular tracksection A or B will cause a shunt across the track rails 2 and 3' anddeenergize its respective track relay R1 or R2. The deenergization ofeither track relay R1 or R2 causes operation of the warning devices WLand WB and deenergization of an actuating relay AR which controlstheoperation of the highway crossing gates G1 and. G2 through its contacts4 and 5, allin a manner to be explained hereinafter.

Although forthe purpose of illustration there has been shown only onerailroad track RT. having controlcircuits governed by-movement oftrains: in both directions, it isobvious that therev may be two or moretracks at the highway crossing H and the control circuits may be suchthat they govern the movement of trains-in one direction only on.aparticular. track or both directions. In all instances, however, thecrossing gates G1 and G2 will be: operated. to their horizontalpositions to block the highway crossing H upon the approach of a train.

The highway crossing gates G1 and G2 are located one.v on either sideofthe highway crossing H and the railroad track RT and are positioned toblock the highway traffic lanes. In the drawing illustration there hasbeenshown only the control mechanism of the highway crossing gate G1which is controlled through the contact 4 of the actuating relay AR. Itshould be understood, however, that the control mechanism of gate G2 isexactly the same and is controlled through the contact 5 of theactuating relay AR. A battery B1 is provided tov supply a source ofenergy and a control switch MS Provides a means to cut the source ofenergy olf or on depending upon whether or not the gate is in service.It' should'also be understood that an additional manual control switchcould be provided to operate the gates manually and irrespective of theautomatic control means shown.

Referring now to the gate operating mechanism as shown for the crossinggate G1, the various parts are suitably mounted'in a mechanism casing 6from which protrudes a gate arm operating shaft 7 which carries the gatearm 8. In actual practice, the mechanism casing 6 isadjustably mountedon a pole standard 9, all as shown. in small scale in connection withthe highway crossing layout portion illustrated in FIG. 1A of thedrawing. For convenience in illustrating the invention, the hydraulicapparatus mounted in the mechanism casing 6has been shown in adiagrammatic exploded view on the FIG. 1B portion of the drawings, thecasing 6' being broken away and no attempt'being made to locate thevarious parts accurately.

A" hydraulic cylinder HC is shown pivotally mounted at one end at 10 ona supporting bracket 11 which in turn is suitably mountedon the insideof the casing 6. The hydraulic cylinder HC contains a piston 12 whichdivides the cylinder into two fluid pressure chambers 13 and 14.Attachedto the piston 12 is a piston rod 15 which extends through thefluid chamber 13 and the top end'wall of the hydraulic cylinder HC to apoint 16 where it is pivotally connected to a crank arm 17 which in turnis fixedly splined and held in position on the gate arm operating shaft7. The parts are so proportioned thatthe application of fluid underpressure into eitherofthe chamber 13 or 14 on its respective side of thepiston 12 will rotate the shaft 7 through an arc of approximately 90 ina certain direction depending upon which side oftthe piston receives thepressure application. As the gate arm 8' is fixedly fastened to theshaft 7 this movementis utilized to operate the gate arm 8 from avertical clear position to a horizontal danger indicating position, orvice versa as the case may be. Asshown in. FIG; 1A, suitably mountedrubber bumper blocks 19,,which cooperate'with' adjustable stop bolts20mlocated ona gate shaft bracket 21',- provide a means to limittheextreme gate arm operative positions.

The-fluid supply to the chambers 13 and 14 of the hydraulic cylinder HCiscontrolled by afour-way hydraulic valve 'V4 and a manifold M. Thesethree units are bolted together as shown to form a single assembly, withthe manifold M in the center position, thus reducing to a minimum thenumber of external pipe connections.

The valve V4 comprises a body portion 25, two end cap portions 26 and 27and a plunger 28. This plunger 28 is slidably mounted in the bodyportion 25 and has its ends extending into the end cap portions 26 and27. A piston 29 is attached to the plunger 28 at its end which lieswithin the end cap portion 27 whereas a coil spring 30 is insertedbetween the end cap portion 26 and the other end of the plunger 28. Whenhydraulic fluid under pressure is applied to the underside of the piston29, the plunger 28 is moved in one direction against the bias of thespring '30; whereas the spring 30 forces the plunger 28 in the otherdirection during the absence of fluid pressure on the underside of thepiston 29. This movement of the plunger 28 opens and closes certain ofthe port chambers 31, 32, 33 and 34 located within the body portion 25of the valve V4.

The manifold M acts as a connecting element between the chambers 31, 32,33 and 34 of the valve V4 and the chambers 13 and 14 of .the hydrauliccylinder HC. The manifold M also houses a throttle valve VT as well asproviding connecting ports to apressure accumulator PA, a sump reservoirSR, and a hold clear valve VHC.

The throttle valve VT is of the plug type and has a crosswise portopening 36 therein' which cooperates with port openings 37 in themanifold M. It also has an operating handle 38 attached thereto. Thehandle 38 is connected by means of a link 39 to a clamp 18 which isadjustably fastened to the gate arm shaft 7, so that movement of thegate arm8 causes rotation of the throttle valve VT. Also, the link 39 isadjustably fastened to' the handle 38 at one end and to the clamp 18 atits other end so that the overall operating length of the link 39 may bevaried to regulate the proper amount of movement of the handle 38. Whenthe gate arm 8 is in motion, all exhaust fluid from the chambers 13 and14 of the hydraulic cylinder HC must pass through the port 36 of thethrottle-valve VT. The size of the opening betweenthe ports'36 and 37varies in accordance with the position of port'36' and controls theamount of fluid passing therethrough at given positions. Two small V-shaped notches 35, disposed opposite to each other, are provided on eachend of the'port opening 36 to assure adefinite passage of fluidtherethrough in the extreme operative positions of the throttle valveVT. The arrangement shown is such that gate arm travel speed is slowatboth-the start and finish of the movement due to restricted portopenings whereas the intermediate travel speed of the gate armis fasterdue to unrestricted port openings in the throttle valve VT.

Also employed in connection with the regulation of the fiow of fluid toand from the hydraulic cylinder HC is a speed control valve 51, a flowcontrol valve 52, a check valve 53 and a vacuum relief valve 54. Thespeed control valve 51 is adjustable and is used to control the flow offluid from the chamber 14 of the hydraulic cylinder HC to thesump-reservoir'SR in order to regulate the midstroke of the downmovement of the gate arm 8.-

As previously mentioned, it is contemplated that the gate arm 8 willnormally move downward by gravity but provision is made to drive itdownward if the gravity movement exceeds a certain time'limit. Withrespect to the overall movement, as'the gate arm 8 moves downward by,gravity and forces the piston 12 downward, the adjustable flow controlvalve 52, which has a set capacity less than that of the speed controlvalve 51, will limit the fiow of fluidto the chamber 13 above the piston12. Consequently, there is no overall tendency to normally build up apressure therein. In fact, therewill be a tendency: to create a vacuumin the chamber 13 during the intermediate gate movement which will causefluid to be drawn thereto from the sump reservoir SR through the vacuumrelief valve 54. This will maintain a full supply of fluid in thechamber 13 but it will not be under pressure. It should be noted at thistime that a slight pressure is built up in the chamber 13 at the startof the gate movement due to the limitation of exhaust fluid through thethrottle valve VT as previously mentioned. This is particularlyadvantageous because it provides a starting momentum for thegravity-down movement of the gate arm 8. However, if for any reason thegravity downward movement of the gate arm 8 is retarded, the fluid underpressure entering through the flow control valve 52 will take over anddrive the gate arm downward to its horizontal danger indicatingposition.

The check valve 53 is provided to supplement the flow of exhaust fluidfrom the chamber 13 upon an upward movement of the gate arm 8 and thepiston 12. As the gate arm 8 is always driven upward and the opening inthe flow control valve 52 is restricted, the additional flow through thecheck valve 53 permits fluid to be exhaust-ed from the chamber 13quickly so as not to retard the normal upward movement of the gate arm8.

With regard to the restricted flow control valve 52 and its normaloperation as just described above, it should be understood that incertain crossing gate installations a crossing gate arm which isnormally driven down may be required. In such cases, the restriction ofthe valve 52 may be varied to a full open position so that the fluidsupply under pressure entering the chamber 13 is as great or greaterthan the fluid supply venting from the chamber 14 through the speedcontrol valve 51. Under such conditions, the power down movement of thepiston would surpass the gravity down movement of the gate arm 8 andresult in a full power down operatron.

The hold-clear valve VHC is an electromagnetically operated valve whichis normally energized and held closed to hold the fluid pressure in thelower chamber 14 of the hydraulic cylinder HC when the gate arm 8 is inits vertical position. This hold-clear valve VHC also normally helps tomaintain the fluid pressure in the chamber on the underside of thepiston 29 of the four-way valve V4. In actual practice, this hold-clearvalve VHC is connected directly to the manifold M to further reduce thenumber and length of pipe connections.

The structure of this hold-clear valve VHC in general comprises anelectromagnetic device having holding coils 40, pickup coils 41, cores42, an armature 43, and an armature stop 44. The valve portion of thedevice consists of a body housing 45 having two chambers 46 and 47therein with the valve head 48 positioned adjacent the openingtherebetween. The stem of the valve head 48 extends through the bodyhousing 45 to the outside where it is connected through an adjustabletoggle linkage device 49 and a spring biased rod 50 to the armature 43.The complete assembly is such that with either the coils 41 and 40, or40 alone, energized, the armature 43 is attracted to the cores 42, thuscausing the rod 50 and the linkage device 49 to position the valve head48 so as to close the opening between the valve chambers 46 and 47. Withthe coils 48 and 41 deenergized, the armature 43 drops away and thegravity bias of the armature 43 together with fluid pressure against thevalve head 48 will cause the valve to open and permit the passage offluid from the chamber 47 to the chamber 46.

There is also provided two other electromagnetically operated valves VUand VD which are used in connection with the operation of the four-wayhydraulic valve V4. When energized and open, the valve VU permits theflow of fluid under pressure to the underside of the piston 29 tooperate the valve plunger 28 to its upward position against the bias ofthe spring 38 as shown. When energized and open, the valve VD permitsthe quick exhaust of this fluid under pressure from the underside of thepiston 29 to the sump reservoir SR, thus allowing the spring 30 tooperate the valve plunger 28 to its downward position. With both of thevalves VU and VD closed and the hold clear valve VHC also closed, thefluid pressure is trapped and maintained on the underside of the piston29 so that the plunger 28 of the fourway hydraulic valve V4 is held inits upward position. Thus, fluid under pressure is normally maintainedto the chamber 14 of the hydraulic cylinder HC through the chambers 33and 34 of the valve V4 to hold the gate arm 8 in its vertical clearposition. However, provision is made to vent the fluid from theunderside of the piston 29 of the four-way valve V4 through a checkvalve 70 to the hold-clear valve VHC in case of a power failure, as willbe explained more in detail hereinafter.

The gate arm shaft 7 is provided with cams 55, 56, and 57 which operatetheir respective biased contact fingers 58, 59 and 60 to control theenergization of the coils 41 of the hold-clear valve VHC, the coil 61 ofthe valve VU and the coil 62 of the valve VD, in a manner to beexplained hereinafter. These earns 55, 56 and 57 are fastened directlyto the shaft 7 and rotate therewith.

The hydraulic fluid for operating the gate arm 8 is supplied through apressure line 71 by a pressure accumulator PA which is precharged withgas and in which the fluid pressure is maintained by automatic pumpingapparatus. This automatic pumping apparatus includes a gear pump Poperated by an electric motor MO which is controlled by a motor relay MRand a pressure switch PS. A sump reservoir SR is provided to store theexcess supply of hydraulic fluid. There is also provided a relief valveVR which vents the pressure line 71 to the sump reservoir SR in theevent that the pressure exceeds certain limitations due to faulty pumpoperation. A check valve 72 inserted in the line between the pressureline 71 and the pump P prevents leakage of fluid from the pressure line71 back through the pump P.

The pressure switch PS is connected into the pressure line 71 and isfluid pressure operated against a biasing spring, whereby a drop ofpressure in the line '71 to a certain limit will cause its electricalcontact 73 to close a circuit and operate the motor MO and the pump P.The circuit for the motor MO is controlled through a motor relay contactfinger 74 rather than directly through the pressure switch contact 73 toobviate the possibility of the heavy motor starting load burning thehighly sensitive pressure switch contact 73. However, it should beunderstood that a heavy duty type toggle contact or mercury switch couldbe used on the pressure switch PS and the motor relay MR could beeliminated.

The control circuit for the automatic operation of the pressure pump Pmay be traced as follows; from the positive side of the battery B1, wire75 through the closed contact of the manual controlled service switchMS, wires 76, 77 and 78, through the pressure switch contact 73 in itsclosed position, wire 79, through the winding of the motor relay MR, andwires 80, 81, 82 and 83 back to the negative side of the battery B1.With the motor rela-y MR now energized, the energizing circuit throughthe motor MO is completed through the first part of the above circuitjust traced to the wire 77, then through wire 84, motor relay contactfinger 74 and its front contact now closed, wire 85, armature of themotor MO, wire 86, and then through wires 81, 82 and 83 to the negativeside of the battery B1. When the fluid pressure in the pressureaccumulator PA and the pressure line 71 again reaches its prescribedlevel, the contacts 73 of the pressure switch PS will again open andstop operation of the pump P.

, With reference now to the operation of the highway crossing gateapparatus described in detail above, as previously mentioned, the normalposition of the gate arm 8 is its vertical clear position as shown onthe drawings. Under normal operating conditions, the gate arm 8 will bemaintained in this vertical position as long as the track sections A andB remain unoccupied by a train.

This is true because the pressure accumulator is supplying a constantsupply of hydraulic fluid under pressure to the'chamber 14 on theunderside of the piston 12 of the hydraulic cylinder HC, which pressureis maintained becausethe'electro-magnetic valves VU and VD and thehold-clear valve VHC are now closed.

This source of fluid supply may be traced from the pressure accumulatorPA through the supply line 7 1 to the port opening 87 of the manifold M,through the chambers 33 and 34 of the four-way valve V4 in its upwardposition andt hrough the port openings 88 and 89 of the manifold M tothe chamber 14 of the hydraulic cylinder HC. Fluid under pressure isalso present on the valve head 48 'of the hold-clear valve VHC and issupplied through the port opening 90 in the manifold M, then through thespeed control valve 51 and the line 91 to' the chamber 47 of thehold-clear valve VHC. Fluid under pressure is also present in the capchamber '27 and the lines 92 and 93 and is trapped by the closed valvesVD and VHC to maintain the piston 29 of the four-way valve V4 in its upposition so long as the gate arm 8 remains in its upward verticalposition. This trapped fluid entered. the valve V4 through the line 94,valve VU in its open position and hne 92 during the upward movement ofthe gate arm 8 when the coil 61 of the valve VU was energized.

Thus, with reference to the normal operation of apparatus justdescribed, it can be seen that so long as the hold-clear valve VHCremains energized and in its closed valve position, the gate arm 8 isretained in its normal vertical clear position. This energizing circuitfor holding the valve VHC closed may be traced as follows: from thepositive side of the battery B1, wire 75 through the closed contact ofthe manual controlled service switch MS, wires 76, 95 and 96, contactfinger 4 and its front contact of the actuating relay AR in itsenergized position, wires 97 and 98, through the coil windings 40 of thehold-clear valve VHC, and wires 99, 100, 82 and 83 back to the negativeside of the battery B1.

As previously mentioned, the electro-magnetic valve VDwhich controls thequick exhaust of fluid under pressure from theunderside of the piston 29of the four-way valve V4 is now closed and in its normal spring biasedposition. The energizing circuit for the coil 62 of this valve VD, whichwill be traced in detail hereinafter, passes through the contact finger101 and its back contact of the hold-clear valve VHC, so that the valveVD is energized and open only when the hold-clear valve VHC isdeenergized and open. Thus, the apparatus is so regulated that the fluidunder pressure in both the four-way valve V4 and the chamber 14 of thehydraulic cylinder HC will be vented at the same time to permit the gatearm 8 to move downward to a horizontal danger indi cating position.

Let us assume now that a train enters the highway crossing track sectionA under normal conditions wherein the highway crossing gates G1 and G2would be lowered to their horizontal danger indicating positions. Underthis condition the train would shunt the track relay R1 and drop itsarmature and contact fingers "132 and 133 to a back contact position.This action would break the energizing circuit for the actuating relayAR at the open contact 133, which circuit may be traced from thepositive side of the battery B1 through wires 102 and 103, contactfinger 134 and its front contact of the relay R2, wire 104, contactfinger 133 and its front contact of the relay R1, wire 105 through thewinding of the relay AR, and wires 106 and 83 back to the negative sideof the battery B1. Also, with the track relay R1 now deenergized, thecircuits through the usual flashing warning lights WL and warning bellWE are completed to warn approaching highway traflic that a train isapproaching the intersection andthat the crossing gates are about to belowered. This procedure is standard practice and the simple circuits maybe traced from the positive n U side of the battery B1 through wires 102and 64, contact 132 and its back contact of the relay R1, wire 65,through the warning devices WL and WB, wires 66, 106 and 83 back to thenegative side of the battery B1. Energy to the flashing warning lightsWL is regulated by a flashing device 67.

With the actuating relay AR now deenergized and its armature and contactfingers 4 and 5 dropped away and in their open positions, the energizingcircuits for the hold-clear valves VHC which control the down movementsof the gates G1 and G2 will now be open. As previously mention, thecontrol systems for the two gates are identical and only the functionsof the gate G1 which are controlled by the contact finger 4 of theactuating relay AR will be shown and described herein.

With the energizing circuit for the hold-clear valve VHC as describedpreviously in detail now open at the contact 4 of the actuating relayAR, its armature 43 will drop away and by means of the rod 50 and thetoggle link arrangement 49, its valve head 48 will be withdrawn to openthe valve port between the chambers 46 and 47 in the main valve body 45.Also, the contact finger 101 attached to the armature 43 will also openits front contact and make its back contact so that the energizingcircuit for opening the electromagnetic valve VD Will be completed andmay be traced as follows: from the positive side of the battery B1, Wirethrough the contact of the manual controlled service switch MS, wires76, 95 and 107, front contact and contact finger 60 associated with thecam 57, Wire 108, coil winding 62 of the valve VD, wire 109, contactfinger 101 and its back contact now in its closed position, wires 110,111, 100, 82 and 33 back to the negative side of the battery B1.

With the valves VHC and VD now both open, pressure behind the piston 29of the four-way valve V4 and the piston 12 of the hydraulic cylinder HCis vented to the sump reservoir SR. The flow of fluid from the fourwayvalve V4 may be traced from the chamber on the underside of the piston29 through the line 92, through the open port of the valve VD now in itsenergized open position, then through the line 112 and the main exhaustline 113 to the sump reservoir SR. The venting of the fluid underpressure from the underside of the piston 29 permits the four-way valveV4 to assume its down position by reason of the biasing spring 30. Thiscauses a shifting of the valve plunger which closes the port openingbetween the chambers 33 and 34, opens'the port opening between thechambers 32 and 33, and closes the port opening between the chambers 31and 32.

With the valve V4 in this down position, the supply of fluid underpressure from the main supply line 71 is diverted from the chamber 14through the restricted flow control valve 52 to the chamber 13 of thehydraulic cylinder HC, as will be explained in detail hereinafter. Also,the gate arm 3 will now start its normal gravity downward movement to ahorizontal position due to the loss of pressure in the chamber 14 of thehydraulic cylinder HC. As previously mentioned, this gravity downwardmovement receives a power assist at the start because the restrictedamount of fluid under pressure entering the chamber 13 at this time isslightly greater than the supply of exhaust fluid leaving the chamber 14by the way of the throttle valve VT. The fluid from the chamber 14 willnow vent through the port openings 89 and in the manifold M, through therestricted speed control valve 51, line 91, chambers 47 and 46 of theholdclear valve VHC now in its open position, line 114 to the portopenings 37 in the manifold M and through the port 36 in the throttlevalve VT, then through the main exhaust line 113 to the sump reservoirSR.

The rate of speed at which the gate arm 8 travels through its midstrokeduring its gravity downward movement is controlled primarily by theadjustable restricted speed control valve 51 and secondly by thevariable port opening 36 in the throttle valve VT. Under normaloperating conditions, the speed control valve 1 is set to permit acertain rate of fluid flow therethrough so that a definite amount oftime is required to exhaust the fluid from the chamber 14 during agravity downward movement of the gate arm 8. The rate of flow of thisexhaust fluid to the sump reservoir SR is further controlled by thethrottle valve VT which is operated in accordance with the gate armmovement as previously explained. The control is such that the rotatablemovement of the throttle valve VT positions its port 36 to restrict theopening and the flow of fluid therethnough at the start of the gatemovement thus assuring a slow starting movement. As the gate armmovement progresses, the throttle valve VT rotates accordingly so thatits port opening 36 lines up fully with the port opening 37 in themanifold M and permits the full flow of fluid therethrough, thusallowing maximum gate arm movement through its intermediate travelperiod. Again, as the gate arm movement approaches its horizontal dangerposition, the port opening 36 in the throttle valve VT starts to moveout of line with the port opening 37 in the manifold M and thusrestricts the flow of fluid therethrough so that the movement of thegate arm 8 is retarded to the extent that it slows up as it approachesits stop position. This assures a cushioned stopping movement andprevents damage to the gate arm 8 and its associated operatingmechanism.

During this normal gravity downward movement of the gate arm 8 and itsassociated piston 12 of the hydraulic cylinder HC, fluid under pressureis permitted to flow into the upper chamber 13 at a restricted rate aspreviously mentioned. When the plunger 28 of the four-way valve V4shifted, the flow of fluid from the main pressure line 71 was divertedfrom the chamber 14 to the chamber 13 through a path which may be tracedfrom the port opening 87 of the manifold M, chambers 33 and 32 of thevalve V4 now open, port opening 115 of the manifold M, line 116, throughthe restricted flow control valve 52, line 117 and through the portopening 118 in the manifold M to the chamber 113 of the hydrauliccylinder HC. The restricted flow control valve 5-2 is adjusted so thatthe passage of fluid into the chamber 13 is at a slower rate than theexhaust of fluid from the chamber 14. This action tends to create avacuum in the chamber 13 which causes additional fluid, not underpressure, to be drawn into the chamber 13 from the sump reservoir SRthrough the line 113, port opening 37 of the manifold M, vacuum reliefvalve 54 and port openings 119 and 118 of the manifold M. Thus, thesupply of fluid is kept full in the chamber '13 but it is not normallyunder pressure during the intermediate gravity downward movement of thepiston 12.

As previously mentioned, the present invention also provides a meanswhereby the gate arm 8 will be driven down by fluid under pressure inthe event that the normal gravity downward movement exceeds theprescribed time limit for which the movement is set. Under adverseconditions such as extreme cold weather, high opposing winds and thelike, there is a possibility that the gravity forces may be curtailed tothe extent that the downward movement of the gate lags appreciably, thuspresenting a dangerous situation as the gate arm 8 may not be down bythe time the train arrives at the highway crossing H. If we assume thatthe normal gravity down-ward movement is set for approximately twelveseconds timing, then the power down movement would be adjusted to takeapproximately fifteen seconds, thus providing a three second lag.

Let us now assume that for reasons stated above the gravity downwardmovement of the gate arm 8 is retarded. As previously stated, thechamber 13 is fully supplied with fluid but it is not normally underpressure. It can readily be seen that as the gravity movement of thepiston 12 slows down below normal that the delayed action of therestricted amount of fluid under pressure entering the chamber 13 willamount to more than the amount 10 of fluid being exhausted from thechamber 14. This results in a build up of pressure in the chamber 13against the top side of the piston 12 which takes over and forces thepiston 12 and its associated gate arm 8 to their downward positions.Although the driving rate of downward movement is not as great as thenormal gravity downward movement because of the restriction of the flowof fluid through the flow-control valve 52, the gate arm 8 willeventually reach its downward horizontal position at a time somewherebetween the twelve second and fifteen second time limits which werechosen above for the purpose of illustration. The net result is that thegate arm 8 will be down and protecting the highway crossing within thetime limit permissible regardless of whether it is a gravity down or adrive down movement or partially both.

Referring now to the operating characteristics of the cams 55, 56 and 57which rotate with the gate arm shaft 7 to operate their respectivebiased contact fingers 58, 59 and 60. The cams are so proportioned thatcams 55 and 56 close their respective contacts 58 and 59 afterapproximately fifteen degrees of rotary movement upon a downwardmovement of the gate arm 8 whereas the cam 57 will open its contact 60'just prior to the completion of the downward movement of the gate arm 8.Although the cam contacts 58 and 59 are closed shortly after thedownward movement of the gate arm 8 begins, this has no effect on theoperation of the system until the gate arm 8 is ready to be returned toits vertical position, as will be explained shortly. However, when thecontact 69 opens just prior to the completion of the downward movementof the gate arm 8, the energizing circuit previously described for thecoil 62 of the electromagnetic valve VD will be broken, causing it toclose its valve which closes the vent for the four-way valve V4, thusconditioning the four-way valve for further charging.

The crossing gate arm 8 will remain in its horizontal danger position solong as the train is travelling through the highway crossing tracksection A and over the highway crossing H. Upon passage of the train thetrack relay R1 will again become energized by means of its usual trackcircuit and cause its armature to be attracted and its contact finger 132 to open at its back contact and its contact finger 133' to close atits front contact, thus stopping operation of the warning devices WB andWL energizing the actuating relay AR. With the actuating relay ARenergized, its contact 4 again makes up with its front contact as nowshown on the drawing and certain circuits are completed to energize thepick-up coils 41 of the hold-clear valve VHC and the coil 61 of theelectromagnetic valve VU. The energizing circuit for the holding coils40 of the holdclear valve VHC is also now closed as shown on thedrawings and previously described.

Let us first consider the energizing circuit for the pick-up coils 41 ofthe hold-clear valve VHC. This circuit may be traced from the positive(-1-) side of the battery B1, wire 75 through the closed contact of themanual controlled service switch MS, wires 76, and 96, contact finger 4and its front contact of the relay AR, wires 97 and 120, cam contact 59and its back contact in their closed position, wire 121 and through thecoil windings 41 of the hold-clear valve VHC, wires 122, 111, 100, 82and 83 back to the negative side of the battery B1. With its coils 41now energized and also the coils 40 energized as previously mentioned,the armature 43 of the hold-clear valve VHC is attracted, thus closingthe front contact of its contact finger 101 and also forcing the valvehead 48, by means of the rod 50 and the toggle link arrangement 49, toclose the port between the chambers 46 and 47.

It will :be noted that both the pickup coils 41 and the holding coils 40of the hold-clear valve VHC are energized during the greater part of theupward movement of the gate arm 8 to its vertical clear position. Thisis done because of the back pressure created against thevalve head 48 ofthe hold-clear valve VHC when pressure is applied in the chamber 14 ofthe hydraulic cylinder HC in order to raise its piston 12. This backpressure is greater at the start of the upward movement because, aspreviously mentioned, the flow of exhaust fluid from the chamber 13 isthrough the port opening 35 in the throttle valve VT, which port openingis restricted at this point of operation. In other words, it requiresmore magnetic force to hold the valve head 48 closed during the startand the first part of the upward movement of the gate arm 8 than it doesto move the gate arm 8 through the last part of its upward cycle and tomaintain it in its upward vertical position. Consequently, the pick-upcoils 41 are open circuited through the cam contact 59 as the gate arm 8approaches its vertical .position and only the holding coils 40 remainenergized to hold the gate arm up, thus saving current.

As mentioned above, the contact finger 101 of the holdclear valve VHC isnow closed so that the energizing circuit for the coil 61 of theelectromagnetic valve VU is also closed. This circuit may also be tracedfrom the positive side of the battery B1 through the contact 4 of therelay AR to wire 97 as mentioned above, then through wire 123 to the camcontact 58 and its back contact in their closed position, wire 124,winding of the coil 61 of the valve VU, wire 125, contact finger 101 andits front contact of the hold-clear valve VHC, wires 110, 111, 100, 82and 83 back to the negative side of the battery B1.

The apparatus is now conditioned so that the normal operation of thegate arm 8 from its horizontal danger position to its vertical clearposition as shown on the drawing may proceed. As the hold-clear valveVHC and the electromagnetic valve VD are now both closed, the flow offluid therethrough to the exhaust line 113 and the sump reservoir SR isblocked. Thus, a flow of fluid under pressure from the main supply line71 and the pressure accumulator PA to the underside of the piston 29 ofthe four-way valve V4 will cause its piston 29 and associated plunger 28to shift to their upward positions against the bias of the spring 30.The fluidpath is from the main supply line 71 through line 94, throughthe open port in the valve VU, then through the line 92 to the chamberon the underside of the piston 29 in the valve V4.

With the four-way valve V4 again in its upward position as shown on thedrawings, fluid under pressure will again flow to the chamber 14 on theunderside of the piston 12 so that the piston 12 and the gate arm 8 willstart their upward movement. The fluid path is from the main supply line71 through the port opening 87 of the manifold M, chambers 33 and 34ofthe valve V4 and port openings 88 and 89 of the manifold M to thechamber 14 of the hydraulic cylinder HC.

As'the piston 12 moves upward, the fluid in the chamber 13 will exhaustto the sump reservoir SR through the port opening 118 in the manifold M,line 117, through the restricted flow control valve 52 and the checkvalve 53 in multiple, line 116, port opening 115 in the manifold M,chambers 32 and 31 of the valve V4, port openings 37 in the manifold Mand port opening 36 in the throttle valve VT, then through the mainexhaust line 113. Here again, the exhaust route is through the throttlevalve VT which assures a slow starting movement of the gate arm 8, amaximum intermediate movement and a slow retarding movement just priorto reaching its stop position. The addition of the check valve 53permits a full fast exhaust of the fluid from the chamber 13 as the flowcontrol valve 52 is necessarily restricted as mentioned hereinbefore tocontrol the input of fluid into the chamber 13.

Under normal conditions, the gate arm 8 will continue its upwardmovement until it reaches its vertical clear position as now shown onthe drawings. On its way upward the gate arm 8 through its shaft 7 willrotate the cams 55, 56 and 57 clockwise, thus again 12 opening the camoperated contacts 58 and 59 and closing the cam operated contact 60',so" that they will be positioned as now shown on the drawings.

The closing of contact 60 occurs shortly after the start of the upwardmovement of the gate arm 8 but it has no immediate affect on theoperation of the valve VD as its energizing circuit is still broken atthe contact finger 101 and its back contact of the hold-clear valve VHC.This circuit will remain open until the valve VHC is deenergized toinitiate a normal downward movement of the gate arm 8, whereupon thevalve VD opens to vent the four-way valve V4 as previously explained.

The opening of contact 59 occurs approximately fifteen degrees beforethe gate arm 8 reaches its upward vertical clear position. This opensthe energizing circuit for the pick-up coils 41 of the hold-clear valveVHC which was described hereinbefore. However, the hold-clear valve VHCremains energized and closed as its holding coils 40 are still energizedby means of a separate direct circuit described hereinbefore.

The contact 58 also opens at approximately fifteen degrees before thegate arm 8 reaches its upward vertical clear position and breaks theenergizing circuit for the electromagnetic valve VU. This causesdeenergization of its coil 61 and permits the valve to close, thusstopping the flow of fluid under pressure to the four-way valve V4. Theclosing of this valve VU also completes the trapping of the fluid underpressure already in the valve V4 as the valves VD and VHC are alreadyclosed. Thus, under normal operating conditions, the four-way valve ismaintained in its upward position until the fluid is vented by theopening of the valve VD as previously explained.

With the gate arm 8 again in its normal vertical clear position, itshould remain in such a position until another train enters the highwaycrossing track section A, whereupon the down cycle of the gate willagain be repeated, all as illustrated and described hereinbefore.However, under abnormal conditions, such as a loss of fluid pressure ora current failure, certain provisions are made in the present inventionso that the gate arm 8 will assume a horizontal danger indicatingposition to conform to standard railway signaling fail-safe practice.

If, due to a leak in the main pressure line 71 or any other part of thepressure system, a loss of fluid pressure should occur with the gate arm8 in its vertical clear position, the pressure drop in the chamber 14 onthe underside of the piston 12 of the hydraulic cylinder HC would permitthe gate arm 8 to start down because of its gravity bias. When the fluidis completely exhausted, the gate arm 8 would eventually assume itshorizontal danger indicating position and remain in such position untilrepairs were made. Also, it should be obvious that a failure of thehold-clear valve VHC, such as a leak or improper closing of its valvehead 48, will cause a pressure drop in the chamber 14 of the hydrauliccylinder HC and permit the gate arm 8to drop to its horizontal dangerindicating position. Furthermore, a pump failure, either due tomechanical or electrical reasons, resulting in a lack of pressure, wouldcause the gate to remain in a horizontal danger indicating position.

Upon an electrical power failure which would cause the hold-clear valveVHC to become deenergized, the gate arm 8 would immediately start itsdownward cycle to a horizontal danger indicating position. In such anevent, however, the descent would be slower than normal be cause thefour-way valve V4 must vent through the check valve and the hold-clearvalve VHC rather than through the valve VD which would also bedeenergized and closed due to loss of power.

Having thus shown and described one specific form which the presentinvention can assume and the manner in which it is to be performed, itis desired to be understood that such form was chosen more for thepurpose of illustrating the principles and mode of operation rather thanfor indicating the full scope thereof. It should be further understoodthat various modifications, adaptations and alterations may be appliedto the specific form shown within the scope of the present invention,except as limited by the appending claims.

What I claim is: 1. In a system for regulating the rotary movements of amounted gate arm at a highway crossing between a substantially verticalposition and a substantially horizontal position and vice versa, thecombination compris- (a) a cylinder having two exteriorly communicatingports and a piston movably positioned within said cylinder and betweensaid two ports for dividing said cylinder into two chambers each havingan area only as limited by the position of said piston,

(b) said piston having an arm connected thereto and positioned at leastpartially exterior to said cylinder and connected to said gate arm to bemovable according to said rotary movements thereof,

() means including a track circuit operatively connected to a railwayresponsive to the absence of a train for providing one distinctivecontrol and responsive to the presence of a train for providing a seconddistinctive control,

(.d) a two-position valve having a plurality of port openinginterconnections in each of two operative positions and having a movableelement biased in one of said two positions for selecting one pluralityof port opening interconnections and forcibly movable to the second ofsaid two positions for selecting a second plurality of port openinginterconnections,

(e) a first electromagnetic means responsive to said one distinctivecontrol for applying said force to said movable element,

(f) a second electromagnetic means responsive to said second distinctivecontrol for relieving said force applied to said movable element,

(g) a pressure accumulator having a supply of fluid maintained under aconstant pressure of at least a predetermined value,

(h) a sump reservoir having a capacity for receiving and storing asupply of fluid,

' (i) a plurality of fluid passageways one for connecting each of saidpressure accumulator, said sump reservoir, said upper chamber and saidlower chamber to particular port openings of said two-position valve,

(i) said two-position valve in said second position being effective toconnect through a passageway said pressure accumulator to said chamberbelow said piston through one pair of interconnected port openings ofsaid one plurality thereof and to connect through a passageway said sumpreservoir to said chamber above said piston through a second pair ofinterconnected port openings of said one plurality thereof for operatingsaid gate arm from a horizontal to a vertical position,

(k) said two-position valve in said one position being effective toconnect through a passageway said sump reservoir to said chamber belowsaid piston through one pair of interconnected port openings of saidsecond plurality thereof and to connect through a passageway saidpressure accumulator to said chamber above said piston through a secondpair of interconnected port openings of said second plurality thereoffor operating said gate arm from a vertical to a horizontal position,

(I) a throttle valve rotatably positioned in a common passagewayextending between said sump reservoir and said two-position valveselectively connected to each of said two chambers,

(m) said throttle valve being interconnected with said gate arm androtatably movable as said gate arm is operatively moved,

(11) said throttle valve having a port opening formed therein of a shapeto permit fluid flowing from either said upper chamber or said lowerchamber according to the existing gate arm position to be variablylimited from a limiting open position as said gate arm rotatably movesfrom the existing gate arm position to substantially an intermediategate arm position wherein said throttle valve port opening is positionedto be fully opened and therein ineffective to limit said fluid flow andto an opposite gate arm position with said fluid flow being variablylimited as said throttle valve port opening is rotatably positioned froma fully opened position to a limiting open position.

2. The system according to claim 1 wherein,

(a) said throttle. valve is of the plug type having a crosswise portopening cut therein of a size to cause said throttle valve to berendered ineffective in substantially the intermediate gate arm positionfor limiting fluid flow therethrough and having V-shaped notches cut insaid throttle valve at each end of said crosswise port opening anddisposed oppositely thereat for providing a passageway for fluid flow ineach of said horizontal and vertical positions of said gate arm.

3. In a system for regulating the rotary movements of a mounted gate armat a highway crossing between a substantially vertical position and asubstantially horizontal position and vice versa, the combinationcompris- (a) a cylinder having two exteriorly communicating ports and apiston movably positioned Within said cylinder and between said twoports for dividing said cylinder into two chambers each having an areaonly as limited by the position of said piston,

(b) said piston having an arm connected thereto and positioned at leastpartially exterior to said cylinder and connected to said gate arm to bemovable according to said rotary movements thereof,

(0) a two-position valve having a plurality of port openinginterconnections in each of two operative positions and having a movableelement biased in one of said two positions for selecting one pluralityof port opening interconnections and forcibly movable to the second ofsaid two positions for selecting a second plurality of port openinginterconnections,

(d) a pressure accumulator having a supply of fluid maintained under aconstant pressure of at least a predetermined value,

(e) a sump reservoir having a capacity for receiving and storing asupply of fluid,

(f) a plurality of fluid passageways one for connecting each of saidpressure accumulator, said sump reservoir, said upper chamber and saidlower chamber to particular port openings of said two-position valve,

0 (g) said two-position valve in said second position being effective toconnect through a passageway said pressure accumulator to said chamberbelow said piston through one pair of interconnected port openings ofsaid one plurality thereof and to connect through a passageway said sumpreservoir to said chamber above said piston through a second pair ofinterconnected port openings of said one plurality thereof for operatingsaid gate arm from a horizontal to a vertical position,

(h) said two-position valve in said one position being effective toconnect through a passageway said pressure accumulator to said chamberabove said piston through a pair of interconnected port openings of saidsecond plurality thereof for operating said gate arm from a vertical toa horizontal position,

(i) a plurality of cams each positioned to be rotatable with said gatearm and each having a similar contour,

(j) a plurality of contact fingers one for each of said plurality ofcams,

(k) each contact finger being engageably biased toward its respectivesaid cam and mounted to be at least 15' partially movable when adifference in cam contour is engageably present,

(I) a plurality of contact points one for each of said plurality ofcontact fingers positioned to be electrically connected to itsrespective contact finger when that contact finger is moved by itsrespective said cam,

(m) means including a track circuit operatively connected to a railwayresponsive to the absence of a train for providing one distinctivecontrol and responsive to the presence of a train for providing'a seconddistinctive control,

(n) an electromagnetic control means having a valve and being'responsiveto said one distinctive control for maintaining said control meansin'one of two positions and further maintaining said valve in a closedposition and operative to a second position in the absence of said onedistinctivecontrol,

() a first electromagnetic valve means responsive to said onedistinctive control dependent upon'a said contact finger and a saidcontact point associated therewith being electrically connected and saidcon trol means being in its said one position and operative to an openposition,

(p) a fluid passageway connecting said-pressure accumulator to a chamberincluded with said twoposition valve through said first valve means tocause thefluid supplied thereto to force-said movable element to saidsecond position,

(q) a second electromagnetic valve means responsive to control energysupplied thereto dependent upon a said contact finger and a said contactpoint associated therewith being electrically connected and said controlmeans being in its second of said two positions,

(r) a first fluid passageway connecting said chamber of saidtwo-position valve to said sump reservoir through said second valvemeans in its responsive condition to cause the fluid therein to bevented to said sump reservoir,

(s) a second fluid passageway connecting said lower chamber of saidcylinder to said sumpreservoir through said valve of said control meansin its-second of said two positions to cause the fluid therein to bevented to said sump reservoir.

4. The system according to claim 3 wherein,

(a) at least two of said plurality of cams each having a contour thereofwhen positioned to engageably bias their'respective said contact fingersinto electrical connection with said respective said contact pointsafter said gate arm has moved from its vertical position through an arcof approximately fifteen degrees,

(11) one of said electrically connected contact fingers being effectiveto electrically connect said onedistinctive control to said controlmeans,

(0) the other of said electrically connected contact fingers beingeffective to electrically connect said one distinctive control to saidfirst valve means,

(d) a third of said plurality of cams having a contour thereofwhenpositioned in the vertical position of said gate arm to engageablybiasits respective said contact finger into electrical connection with itsrespective said contact point for supplying said control energy to saidsecond valve means until said gate arm arrives at a point in itsrotational travel from a vertical position to immediately prior to thehorizontal position thereof'whereat the contour of said third campermits its associated said contact finger to be electricallydisconnected from its respective said contact point.

5. The system according to claim 4, wherein (a) said control means is arelay having a holding coil and a pick up coil,

(b) said holding coil being responsive to said one distinctive control,

(0) said pick up coil being responsive to said one distinctive controlaccording to said one contact finger being electrically connected to itsrespective said contact point,

(d) said relay having an armature and a front contact electricallyconnected when said one distinctive control is supplied to said holdingcoil or said pick up and said holding coil for completing an electricalcircuit for energizing said first electromagnetic valve means,

(e) said relay further having a back contact electrically connected whensaid one distinctive control is absent for completing an electricalcircuit through said armature for energizing said second electromagneticvalve means,

( f) means connected to said armature effective in the picked upposition of said relay to close said valve of said control means forprohibiting the flow of fluid from said lower chamber to said sumpreservoir and effective in the dropped away position of said relay toopen said valve for permitting said fluid to flow.

6. The system according to claim 3, wherein (a) a speed control valve isincluded in said second fluid passageway and adjustable for limiting theflow of fluid from said lower chamber of said cylinder,

(b) a flow control valve included in said passageway between said upperchamber and one of said interconnected port openings and adjustable forlimiting the flow of fluid to said upper chamber of said-cylinder fromsaid pressure accumulator,

(c) said flow control valve being adjustable to a maximumopening lessthan the maximum opening to which said speed control valve is adjustableso as to limit the flow of fluid to said upper chamber of said cylinderand permit gravitational forces exerted on said gate arm to regulate itsdownward speed according to the adjustment of i said speed controlvalve,

(d) a vacuum relief valve included in a fluid passageway connecting saidsump reservoir to said upper chamber and being biased normally to aclosed position but forcedto an open position as determined by a vacuumestablished in said upper chamber during the venting of said lowerchamber for supplying fluid from said sump reservoir to said upperchamber.

References Cited in'the file of this patent UNITED STATES PATENTS431,732 Waylandet al. July 8, 1890 740,907 Page Oct. 6, 1903 982,088Orlopp Jan. 17, 1911 1,077,558 Rodgers et al. Nov. 4, 1913 1,251,218Gonzales Dec. 25, 1917 1,388,674 Tsenes Aug. 23, 1921 1,480,170 LoganJan. 8, 1924 1,938,192 Meyer et'al. Dec. 5, 1933 1,993,533 Staley Mar.5, 1935 2,164,911 Garverick- July 4, 1939 2,209,594 Bragg July 30, 19402,276,016 Brantly Mar. 10, 1942 2,321,874 Tandler et'al. June 15, 19432,598,196 Staley May 27, 1952 2,649,841 Jacques Aug. 25, 1953

